Spun yarns, which are those made up of synthetic or natural staple fibers, are easily recognized as yarns possessing fiber ends protruding from the surface of the yarn. They are further recognized as being either twisted or fasciated in structure. A twisted yarn, typically manufactured by ring spinning, possesses torque or twist liveliness. A twisted yarn that has twist liveliness, when held by both ends, will spontaneously curl around itself. A close examination of the yarn reveals that the fibers are held together in a helical pattern.
Fasciated yarns are recognized as yarns without twist liveliness and are typically manufactured by open-end rotor spinning or air jet spinning. A close examination of these yarns reveals a longitudinally well-ordered bundle of fibers that are in substantially parallel alignment with the bundle being wrapped by fibers that wind around surface of the bundle.
The orientation of the surface wrapping fibers is different for fasciated open-end yarns and fasciated air jet spun yarns. Air jet spun yarns typically possess wrapping fibers that are predominantly helically wrapped in one direction around the bundle of substantially parallel fibers. The wrapping fibers of open-end spun yarns tend to be more random with the direction and angle of wrapping being different for different fibers. A non-fasciated segment of a yarn has no, or at most an insignificant number of, surface wrapping fibers.
The widely accepted method of producing air jet spun yarns is with a pair of torque jets in series, which imposes false twist to the yarn in opposing directions. A sliver passes into a cylindrical yarn cavity of the body of an air jet for consolidation therein to form a yarn. The torque jets provide air inlet bores impinging on the yarn cavity such that there is an offset between the axis of the air inlet bore and the center line of the yarn cavity. Because of this offset, the air from the air inlet bore impinges the yarn tangentially and imparts torque to the yarn. False twist is a temporary twist imparted to the yarn or sliver on the inlet side of a twisting jet, such as the torque jet described above.
Continuous filament yarns are easily recognized by the absence of fiber ends protruding from the surface of the yarn. One of the many common structures of continuous filament yarns are interlaced yarns. These yarns are noted for their repeating pattern of tight nodes, or interlace points, separated by open segments of parallel filaments which are not held together by looped or wrapping fibers. Typical interlace points are characterized by a random tangling of fibers which form a structure such as a knot in which the fibers are snarled or randomly entangled or laced together, as shown in FIG. 2. The tightness and spacing of the interlace points and open segments are the subject of many variations that are manufactured using interlacing jets of many designs. Typically, there are also no fiber ends protruding from the surface of interlaced yarns unless they are post treated with an abrading technique. The process of air jet texturizing of continuous filament yarns is greatly enhanced by wetting the yarn before it enters the interlacing jet. Many devices exist to provide the wetting function such as metered slot applicators, gravity fed slot applicators, and spraying devices. This method, however, is not currently known or practiced in the production of spun yarns.
A need remains to produce yarns having elongation and tenacity properties similar to those of interlaced continuous filament yarns but exceeding those of spun yarns made by conventional spinning equipment, and that need is addressed by the method, apparatus and yarn of this invention.